Bos's 85th-minute winner papered over what was one of the most underwhelming performances of the Tony Popovic era.
In front of a crowd of 23,798 at Stadium Australia on Friday, the Socceroos struggled to create or challenge their opponents in the final third.
The introduction of Nestory Irankunda - deployed as a striker rather than a winger - in the second half seemed to offer Australia a point of difference.
"The first half there were a lot of new boys and we looked a little bit anxious," Popovic said.
"I thought we created some good openings but didn't finish the chances.
"It was a little bit stretched more than what we would have liked.
"I think in the second half we were more compact and aggressive and the players felt a lot more comfortable out on the pitch."
Substitute Ajdin Hrustic missed a penalty soon after being thrown on as Connor Metcalfe's replacement, before Bos capitalised on a Cameroonian mix-up at the back to grab a late winner.
"He (Metcalfe) was coming off regardless, but I think he just got a knock around his knee," Popovic said.
Cameroon failed to qualify for the World Cup but they did a commendable job of boring the Socceroos into submission as the home side failed to register a single shot on target in the first half.
Popovic handed striker Deni Juric and 18-year-old centre back Lucas Herrington their first caps.
Herrington looked reliable, but Juric barely had an opportunity to prove his worth to lead the line in June, with the Wisla Plock forward feeding off scraps.
Australia were disciplined but lacked any real creative spark, despite the best intentions of Riley McGree and wing-backs Jacob Italiano and Bos.
Juric and Martin Boyle were taken off at halftime and replaced by Irankunda and Awer Mabil.
Immediately there was more zip to Australia's attack, with Irankunda leading the line for the Socceroos and asking questions of the Cameroon defence.
Hrustic was also thrown into the fray soon after the hour mark and had a chance to make himself a hero when he stepped up to take a penalty.
An over-hit Italiano cross found its way to Aiden O'Neill inside the Cameroon box and the midfielder was clumsily brought down by Oliver Kamden in the 66th minute.
Referee Robert Jones pointed to the spot after a VAR check, but Hrustic could only fire straight at Cameroon goalkeeper Devis Epassy.
Epassy then denied Irankunda, and the Watford prodigy lashed another opportunity wide of the post as Australia pressed for a late goal.
Drawn games in the FIFA friendly series are decided via penalty shootout, but Australia avoided the lottery thanks to a blunder from Samuel Kotto.
The Cameroonian defender could not clear a through-ball properly and Bos was on the spot to lash the match-winning goal past Epassy.
14°C